Horizontal output transformer for television receivers



INVENTORSZ WILLIAM L. HUGHES, BENJAMIN O. POWELL,

THEIR ATTORNEY.

United States Patent 3,408,605 HORIZONTAL OUTPUT TRANSFORMER FOR TELEVISION RECEIVERS William L. Hughes, North Syracuse, and Benjamin 0. Powell, Liverpool, N.Y., assignors to General Electric a corporation of New York Continuation of application Ser. No. 539,702, Apr. 4, 1966. This application Feb. 13, 1968, Ser. No. 705,226 5 Claims. (Cl. 336-96) ABSTRACT OF THE DISCLOSURE This invention is directed to a horizontal output trans- This application is a continuation of application Serial No. 539,702, now abandoned, filed April 4, 1966.

The present 3,408,605 Patented Oct. 29, 1968 ingly operates at a relatively high temperature thereby lowering the reliability of the transformer.

Furt er, the requirement that the Additional problems are also found to be associated with the A non-combustible naphthalene chloride wax corona tire is then positioned around the tertiary assembly, the naphthalene chloride wax penetrating the interstices between layers of the polyester film rugged assembly.

FIGURE 3 is a completely assembled of the transformer shown in FIGURE 2.

Referring to the representative horizontal output transformer depicted in FIGURE 1, there is shown generally at 1 a winding having first and second end taps 3 and 5 respectively and including an intermediate tap 7. The

perspective view portion 8 of the winding 1 between the taps 3 and 7 comprises the primary of the transformer while the portion 9 between the taps and 7 comprises the tertiary winding across which the high voltage required for operation of the cathode ray tube is developed. In operation, the tap 7 is connected to the output of the horizontal output stage to couple the desired sweep signal to the primary of the transformer. A high voltage is produced at the high voltage tap 5 and a boost voltage is produced at the tap 3 in conventional fashion. Additional intermediate taps 10 and 11 are provided on the primary of the winding 1, the tap 10 being the conventional yoke tap and thus being connected to the horizontal deflection windings while the tap 11 is the conventional damper tap and accordingly is connected to a suitable damper diode.

In addition to the winding 1, an ancillary winding 13 is provided having end taps 15 and 17. The winding 13 is magnetically coupled to the winding 1 and serves to develop keying pulses across the taps 15 and 17 for the AGC keyer in conventional fashion. In addition to the winding 13 further ancillary windings might be employed. For example, a second ancillary winding might be employed to provide a blanking signal in conventional fashion.

Referring to FIGURE 2. there is shown a horizontal output transformer structure in accordance with the invention, like reference numerals being given to those winding portions identified in FIGURE 1.

The horizontal output transformer of the invention comprises a primary assembly generally shown at 21 and an annular tertiary assembly generally shown at 23. The primary assembly 21 includes a coil form preferably formed from a slow-burning or flame retarding plastic material such as general purpose phenolic. The coil form comprises a generally cylindrical coil supporting portion 25 and an integral generally annular shaped end portion 27 upon which are positioned axially extending terminals 29 in conventional fashion.

The primary portion 8 of the winding 1 shown in FIG- URE 1 and the ancillary winding 13 are wound directly on the coil supporting portion 25, the winding as depicted being of the universal type and employing an insulated magnet wire. A length of adhesive coated tape 31 preferably formed from a slow-burning or flame retarding material such as a polyester film having a thermosetting pressure sensitive adhesive deposited thereon, is positioned over the completed primary winding to retain the winding in the desired position.

The tertiary assembly 23 comprises an open ended cylindrical kraft paper coil form 33. The tertiary winding 9 as shown in FIGURE 1 is layer wound about the coil form 33, the winding 9 preferably being formed from an insulating magnet wire coated with a solvent activated adhesive material. The winding 9 is layer wound as shown, the number of layers and the number of turns in each layer being determined by the electrical requirements of the transformer.

In accordance with an important feature of the invention, the layers of the winding 9 are insulated one from the other by an interleaved film 35 of a slow-burning polyester material. This material is preferably a polyethylene terephthalate film having a thickness on the order of .002, such as for example the commercially available material Mylar. The slow-burning polyester material 35 plays an important role in rendering the horizontal output transformer of the invention non-combustible. Thus, should a malfunction take place in such a manner that localized heat is generated within the tertiary winding, the film 35 in the heated area will melt prior to burning and has a tendency to thicken upon melting to such an extent that combustion is precluded. Since the slow-burning polyester film is non-hygroscopic the impregnating wax employed in the prior art is obviated and the problems associated with such wax are eliminated. For example, it is well known that WaX has a greater dissipation factor than air and that this factor increases markedly as its temperature approaches the operating levels that these transformers are subjected to, e.g., 8Q-l25 C. This tends to increase the internally generated heat which, in the extreme, can lead to thermal runaway. By eliminating wax impregnation, thus leaving the turns of the winding immediately surrounded by air, the transformer operates at a lower temperature than heretofore.

As depicted in output terminal 37 is provided, the terminal 37 being attached to the tertiary assembly '23 by a length of adhesive coated tape 39 preferably of the same type employed for the element 31 and the end of the winding 9 being connected to the terminal 37.

It will be seen that since the tertiary assembly 23 eliminates the necessity for wax impregnation by employing a slow-burning polyester film that the tertiary assembly is truly non-combustible in the sense employed throughout this specification.

Referring to FIGURE 3 there is shown the assembled horizontal output transformer in accordance with the invention. As depicted, the central opening in the annular tertiary assembly 23 receives the primary assembly 21, a suitable adhesive being utilized to attach the kraft paper coil form 33 to the tape 31.

In accordance with another important feature of the invention a non-combustible naphthalene chloride wax corona tire 41 is placed around and in intimate contact with the tertiary assembly 23. A conventional high voltage lead 43 is attached to the terminal 37 shown in FIGURE 2. The lead 43 is provided with an end terminal 45 adapted to engage the high voltage cap of a conventional high voltage rectifier tube. A fire retarding air seal material 47 is molded around the terminal 37 as depicted to preclude corona discharge in the vicinity of the terminal. The transformer is completed by attaching the various taps shown in FIGURE 1 to the associated terminal 29 as depicted.

As pointed out above, the horizontal output transformer of the invention is non-combustible as contrasted to the prior art devices due to the use of the slow-burning polyester insulation and the non-combustible naphthalene chloride wax corona tire.

It will be seen that the transformer in accordance with the invention is much easire to fabricate than the prior art device. Thus, the tertiary assembly 23 is easily gang wound utilizing a single wide sheet of polyester film 35, the adhesive coating on the winding 9 being activated by a suitable solvent so that the winding adheres to the polyester film and does not spread apart or wander during and after assembly. Even where the surface of the film is too slippery for the winding to adhere, the adherence of adjacent turns to each other is sufficient for this purpose. The various tertiary assemblies can then be separated one from the other by a suitable sawing operation.

The corona tire be applied to the tertiary assembly 23 either primary assembly 21 is assembled thereto. If the corona tire is applied prior to assembly, the tertiary assembly 23 is dipped in a hot pool of naphthalene chloride wax. If the corona tire 41 is applied subsequent to assembly, the assembly is supported slightly above the wax pool and parallel thereto so that the tertiary can be rotated through the pool and the corona coating adhered thereto. In either event, it will be appreciated that the corona tire is easily applied to the tertiary assembly 23 since the naphthalene chloride wax quickly freezes to the tertiary assembly 23 and provides a uniform and continuous coating. Further, the naphthalene chloride wax fills the interstices between adjacent layers of the polyethylene terephthalate film and provides an integrated and rugged assembly.

As an alternative to applying the naphthalene chloride wax by a clipping process, it is also possible to use a low molding technique. Such a molding tech- Although the invention has been described with respect to certain specific embodiments, it will be What we claim and of the United States is:

1. A noncombustible horizontal output transformer for a television receiver comprising:

(a) a primary assembly including a coil form having a primary winding positioned thereon, (b) an annular tertiary assembly including an open tioned thereon, adjacent layers of said tertiary winding being separated by a layer of non-hygrosco insulating material formed from a slow-burning p0 ester film,

(c) said tertiary assembly being positioned in coax and surrounding relationship to said primary win ing and being afiixed thereto, and

UNITED STATES PATENTS 2,124,288 7/1938 Dodd 336-96 X 2,282,759 5/1942 Gavitt 336-205 X 2,246,159 6/1941 Work et a1. 336-205X 2,612,545 9/1952 Gray 336206 X 3,225,269 12/1965 Worcester 336206 X 3,263,196 7/1966 Reber 336205 X OTHER REFERENCES The Condensed Chemical Dictionary, Reinhold Publishing Corpartion, Sixth Edition, 1962, page 262 relied upon, copy in Gr. 215.

LEWIS H. MYERS, Primary Examiner. T. J. KOZMA, Assistant Examiner. 

